Tag Archives: Shaft sinking

Murray & Roberts Cementation shaft sinking alternative takes safety to a new level at PMC Lift 2

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The sinking of a 1,200 m ventilation shaft as part of the Palabora Mining Company (PMC) Lift 2 expansion in South Africa is proving to be a partnership success story, based on an unshakeable commitment to safety, according to Murray & Roberts Cementation.

PMC commissioned this new ventilation shaft – which measures 8.5 m in diameter – to service its Lift 2 block cave, awarding the project to Murray & Roberts Cementation in February 2019. Now in its final phases, the project has earned an impressive safety record; it has been fatality-free, and, last year, achieved 574 days without a Lost Time Injury (LTI), the contractor reports.

The Lift 2 project will extend mine life by more than 15 years. Originally an open-pit mine, the Palabora mine transitioned to underground block cave operations in the early 2000s when Lift 1 was commissioned. Back in February, Murray & Roberts Cementation outlined that it had recently celebrated the achievement of a major milestone – reaching the 800 m mark – at the project.

“Feasibility studies indicated that a blind sink was the optimal method, despite its higher cost and longer time frame,” Jas Malherbe, Murray & Roberts Cementation’s Project Manager, explained. “Ground conditions were among the reasons why raiseboring was not an option, as the side walls needed immediate support to prevent scaling.”

Traditionally, the shaft would be lined to within 12-18 m of the shaft bottom, with the sidewalls being temporarily supported with split sets and mesh. However, the difficult ground conditions led to high levels of scaling that made this practice unviable.

“With ground conditions being such a key challenge on the project, we responded in an innovative way by taking the shaft lining right down to the blasted face,” Malherbe says. “The shaft sinking methodology in this project is, therefore, based on the Canadian shaft sinking method pioneered by Murray & Roberts Cementation – but has been adapted to ‘the PMC way’. This has involved lining the shaft to within 1.5 m of the shaft bottom, after mucking out the waste.”

Murray & Roberts Cementation uses a specialised concrete mix for rapid setting and early strength which hardens to 3 MPa within four hours – and this would be in place for at least eight hours before blasting. This solution requires that the blast is conducted while the shutters are still in place – so the shutters are strengthened and a toe added that would better handle the blast. The exposed concrete above the shutter is able to withstand the blast, as it has already cured for 48 hours.

Malherbe explains that drilling is undertaken by two twin-boom electro-hydraulic jumbo drill rigs. These are slung down the shaft from surface and nested in the four-deck stage for drilling the shaft bottom, a procedure which is repeated for each 48 hour blast-to-blast cycle. Waste rock is lashed using an excavator with a 0.36 cu.m bucket, which is lowered from surface through the stage to shaft bottom.

After blasting, an excavator is used for loading rock from the shaft bottom, which is safer than the conventional cactus grab, according to Murray & Roberts Cementation. Ground conditions lend themselves to the generation of large rocks during blasting, which can be difficult to handle. These are broken up using an hydraulic breaker, which can be coupled to the excavator. An 11-t kibble transports the waste rock to surface.

The Lift 2 project will extend mine life by more than 15 years

“Lashing a shaft with an excavator is not a new idea, but it is usually a back-up method to the cactus grab,” Malherbe says. “In this project, we decided that the excavator would be the primary lashing method, to further enhance safety on site.”

Steps have also been taken towards automating the headgear, to avoid the safety hazards of manually hooking the kibble to tip out the waste rock. This includes the winding engine driver being able to use a camera to check for correct hooking.

“We also opted to use electric actuators in this project, rather than the traditional pneumatic and hydraulic cylinders on equipment such as the bank doors, swing chutes and tipping chutes,” Malherbe continues. “This has allowed us to mitigate the risks such as hearing loss from the noise of certain actuators, and contamination from oil leaks.”

According to Sechaba Letaba, PMC’s Package Manager on the project, PMC took a deliberate decision to prioritise safety in the sinking of this ventilation shaft.

“By taking the PMC way, we have accepted that the pace of sinking would have to be compromised,” Letaba says. “This has proved to be a positive approach, as we have an outstanding safety record on the project. This is in stark contrast to the history of shaft sinking, which would often claim lives and cause injuries. We are therefore very proud of what we have achieved to date.”

He highlights the pivotal roles played by Sam Ngidi, PMC Senior Manager Operation & Lift 2 Project, and Aidan Schoonbee, Senior Project Manager Construction – in driving the project and ensuring its success.

Fred Durand, Murray & Roberts Cementation’s Senior Project Manager, points out that unexpected challenges tend to have an impact on scheduling, so the strong relationship of trust with PMC was vital to solving any issues as they arose.

“Our approach has always been to work closely with customers on solutions, and to ensure they are regularly updated on progress,” Durand says. “As a team, for instance, we decided that the rock breaker was the right solution for the issue of oversized rocks, and it was accepted that this would have an impact on the cycle times.”

Similarly, encountering more challenging ground conditions than expected required a significant mindset change about how the team approached the project.

“With the supportive relationship between PMC and Murray & Roberts Cementation, we were able to agree on the necessary remedies and adjust the timeframe to suit our priority – which was safety,” he says.

Malherbe concludes that, for Murray & Roberts Cementation, the lessons learnt on this project have shown the industry a viable alternative method of shaft sinking that takes safety to a new level.

South32 and Redpath kick off shaft sinking works at Hermosa

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South32 has now broken ground on one of two exploration shafts at the Hermosa project in southern Arizona, USA, in a sign of major progress at the base and battery metal project.

This milestone achievement commemorates the initial surface excavation that will be continued by Redpath USA to a planned depth of 900 m, the contractor stated in a LinkedIn post. Redpath and South32 signed a “limited notice to proceed” for shaft engineering and design at Hermosa last year.

Redpath said in this latest post: “The shafts will enable underground access for continued exploration of a world-class deposit containing the US critical mineral zinc as well as lead and silver – minerals needed for supporting electrification and renewable energy.”

In South32’s March quarter results, the company said it invested $176 million over the last nine months as it continued critical path activity and study work for the Taylor zinc-lead-silver deposit and the Clark battery-grade manganese-zinc-silver deposit. It also directed $12 million to capitalised exploration in the nine months ended March 2023 as it continued exploration programs at Taylor and Clark and the copper-lead-zinc-silver Peake prospect 8.

Just last month, the Hermosa project was confirmed by the United States Federal Permitting Improvement Steering Council, an independent federal agency, as the first mining project added to the FAST-41 process, which is focused on supporting informed decision-making while reducing and eliminating unnecessary and costly delays associated with projects.

Anglo American increases Woodsmith polyhalite scale as shaft sinking progresses

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Anglo American is upping the ante at its Woodsmith polyhalite project in the UK, increasing its planned spend while expanding its production scope following detailed design reviews and non-critical path studies.

In the company’s 2022 results release today, it said these reviews and studies had led to a number of areas being modified to align with Anglo American’s standards and its aim to optimise value for the long term.

The outcome is an enhanced project configuration to ensure the company delivers maximum commercial returns from Woodsmith over the expected multi-decade asset life, Anglo said. Included within this is an increase in the capacity of the shafts and other infrastructure to accommodate higher production volumes and more efficient and scalable mining methods over time.

More specifically, this has seen the company plan for a circa-13 Mt/y operation instead of the previous 10 Mt/y operation it had endorsed, subject to studies and approval.

“In light of these changes, Anglo now expects first product to market in 2027, with an annual capital investment of around $1 billion,” the company said.

Spending of $800 million is approved for 2023, with the bulk of initial spend on the shaft sinking and tunnel boring activities. As usual in developing underground mines, the schedule will largely be determined by the ground conditions encountered as sinking activities progress.

The Woodsmith project is located on the North Yorkshire coast, just south of Whitby, where polyhalite ore will be extracted via 1.6-km-deep mine shafts and transported to Teesside via an underground conveyor belt in a 37 km tunnel, thereby minimising any environmental impact on the surface. It will then be granulated at a materials handling facility to produce a low carbon fertiliser – known as POLY4 – that will then be exported from its port facility, where it has priority access, to a network of customers around the world.

During 2022, as part of the mentioned construction review, contracts were awarded for the shaft sinking operations, program management services and construction management to ensure the project can be executed in line with Anglo American’s stringent requirements. These contracts were awarded to Redpath (shaft sinking) and Worley (program management services and construction management).

With the award of these contracts and other infrastructure improvements, activities at the deep shafts have progressed. The service shaft is now more than 360 m deep, while shaft sinking began 120 m below the surface for the production shaft in January 2023, as planned. Both of these shafts are being sunk using Herrenknecht’s Shaft Boring Roadheader technology.

Three intermediate shafts will provide both ventilation and additional access to the mineral transport system (MTS) tunnel. The Lockwood Beck intermediate access shaft was successfully completed in 2022 and is fully lined and connected to the tunnel. Work on the MTS shaft at the mine head progressed through 2022 and is 85% complete, and the excavation at the final intermediate access shaft at the Ladycross site commenced in early 2023.

Following a planned maintenance pause in mid-2022 to refurbish the tunnel boring machine and allow the connection with the Lockwood Beck shaft, the MTS tunnel is now past the 21-km point and is more than 56% complete, progressing at rates not seen since the start of the tunnelling activities, Anglo said.

Anglo American concluded: “We believe that the changes we have made to the project have had a materially positive impact on the project’s long-term attractiveness and prospects. However, for accounting purposes at this early stage of the project’s development, we have recognised an impairment of $1.7 billion to the carrying value of the asset within special items and remeasurements, reflecting the extension of the development schedule and capital budget.”

Murray & Roberts Cementation hits shaft sinking milestone at Palabora

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The Murray & Roberts Cementation shaft sinking team responsible for delivering a new ventilation shaft at Palabora Copper Mine (PMC) recently celebrated the achievement of a major milestone – reaching the 800 m mark.

This milesttone represents two-thirds of the shaft’s final depth of 1,200 m.

The ventilation shaft forms part of the copper producer’s Lift II project, which will extend mine life by more than 15 years. Originally an open-pit mine, the Palabora mine transitioned to underground block cave operations in the early 2000s when Lift 1 was commissioned.

PMC is located within Phalaborwa, in the Limpopo province of South Africa, and the extension of the life of mine will increase shareholders’ value and sustain jobs and livelihoods of the surrounding communities, according to the company. The mine has also initiated several wildlife management programs to minimise the impact of its operations on the environment as well as promote the harmonious co-existence of people, industry and wildlife.

Murray & Roberts Cementation’s contract to sink the 8.5-m diameter shaft was awarded in February 2019. According to Fred Durand, the company’s Senior Project Manager, the shaft sinking is currently making good progress, with 40-or-more lined metres of advance being completed on average each month.

“Shaft sinking operations should be completed by the end of this year with final handover of the shaft to our client, PMC, taking place at the end of the first (March) quarter of 2024,” he says.

Ground conditions have presented a challenge on the project. This has resulted in the shaft lining being taken right down to the blasted face, says Jas Malherbe, Murray & Roberts Cementation’s on-site Project Manager.

“Normally, we would line the shaft to within 12 to 18 m of shaft bottom and support the sidewalls temporarily with split sets and mesh,” he explains. “In practice, this did not prove viable, prompting us to change our approach. The method we’ve adopted is unconventional but has proven to be highly effective.”

Drilling is undertaken by two twin-boom Komatsu electro-hydraulic jumbo drill rigs. These are slung down the shaft from surface and nested in the four-deck stage for drilling the shaft bottom, a procedure which is repeated for each 48-hour blast-to-blast cycle.

Another key piece of equipment is a Komatsu excavator with a 0.3 cu.m bucket. It is lowered from surface through the stage to shaft bottom and is used for lashing. All the waste rock is loaded into a 11 t kibble, which transports it to surface.

The ground conditions at the shaft are such that blasting tends to produce large rocks that can be difficult to handle.

Malherbe said: “We break these up using the excavator, which has a quick coupler which allows it be fitted with a hydraulic breaker within a few minutes.”

The methods being used at Palabora are based on the Canadian shaft-sinking method Murray & Roberts Cementation has pioneered in South Africa at its Venetia mine contract for De Beers Group.

“We have adapted the method because of the very different conditions we’re facing but many elements remain the same or are very similar,” Malherbe said. “In particular, the high degree of safety offered by the Canadian method has not in any way been compromised.”

The number of Murray & Roberts Cementation personnel deployed per shift is 25. The total labour complement on site is currently just over 120 people, 46% of them recruited from local communities.

Murray & Roberts Cementation has a vigorous CSI program running in conjunction with its contract. It is being implemented in close association with PMC and has mainly focused on supporting local schools in the Phalaborwa area with infrastructure such as ablution facilities, fences, water storage tanks and boreholes.

Durand said: “In addition, we have trained nearly 80 youths from local communities at our Bentley Park Training Academy, near Carletonville. Another 20 are currently undergoing training. This program is giving them skills which are in high demand in mining, and which could lead to them securing permanent employment within the mining industry.”

Anglo American continues SBR-led shaft sinking progress at Woodsmith

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While Anglo American continues with its detailed technical review of the Woodsmith polyhalite project in the UK, shaft sinking activities at the asset continue to progress, the company confirmed in an investor update today.

The project was acquired by Anglo American in 2020 with the purchase of Sirius Minerals. Since then, Anglo American has been working on refining the development pathway and overall production potential of the asset.

In an investor presentation today, the company outlined physical progress on the site, explaining that shaft sinking for the circa-1.6-km deep service shaft had progressed to the circa-265-m level. It also said the mineral transport shaft, which it is working on with Redpath Group as sinking contractor, had reached the circa-230-m level of a planned 321-m depth.

Regarding horizontal development, it added that the 37-km mineral transport tunnel – which will connect to the mineral transport shaft – had reached the 20-km development mark with tunnel boring machine technology.

The Woodsmith project overview includes the sinking of production and service shafts with 6.75-m diameters – having depths of 1,594 m and 1,565 m, respectively – and the 37-km-long concrete-lined tunnel containing a conveyor belt, which transports the polyhalite ore from Woodsmith mine, near Whitby, to the Mineral Handling Facility, on Teesside, for processing and shipping.

Both the service shaft and production shaft at Woodsmith are being sunk using Herrenknecht’s Shaft Boring Roadheader technology, which has previously featured on the Jansen potash project in Saskatchewan, Canada, where it excavated two 8-11 m diameter blind shafts down to circa-1,000-m-depth and the Slavkaliy-owned Nezhinsky potash project, where it ended up breaking shaft sinking records under the guidance of contractor Redpath Deilmann on a project to sink two 8-m diameter shafts (one to 750-m depth and one to 697-m depth).

The first cut for the service shaft was made in July 2021, with Anglo American and Redpath Deilmann – which is now leading the sinking project as shaft sinking contractor – restarting sinking activities on this shaft earlier this year.

In the same investor presentation issued today, Anglo American said it planned to start sinking in the production shaft in the March quarter of 2023.

While the ongoing review takes place, Anglo American confirmed it had approved $800 million of capital expenditure for Woodsmith next year, focused on shaft sinking and other critical infrastructure as part of its phased approach to the asset.

Stephen Pearce, Finance Director of Anglo American, said on Woodsmith: “As we have said for some time, we are improving the project’s configuration to ensure we realise the full commercial value over the expected multi-decade asset life. This will extend the development schedule and the capital budget, compared to what was anticipated prior to our ownership, and so potentially impact our carrying value of Woodsmith for accounting purposes at the year end.

“Looking ahead, we are even more positive today about the prospects for Woodsmith and its potential to become a high margin, major contributor to our diversified product portfolio given the outstanding nature of the resource and the premium pricing upside we expect to realise for Poly4 – the highly effective, low carbon fertiliser we will produce.”

Alamos’ Island Gold mine keeps giving up its goods

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The latest drill intercepts from Alamos Gold’s Island Gold Mine in Ontario, Canada, have continued to showcase the potential of an asset that already has a more than 17-year mine life ahead of it, John McCluskey, President and Chief Executive Officer, says.

On the same day as releasing an assortment of promising drill intercepts outside of the existing reserves and resources – namely 110.17 g/t Au over 7.79 m, 97.21 g/t Au over 5.05 m and 525.28 g/t Au over 2.33 m – McCluskey continued to highlight the credentials of an asset that had just 1.8 Moz of mineral reserves and resources, and production around the 100,000 oz/y mark when it was acquired by Alamos in 2017 in a $620 million all-share deal for mine owner Richmont Mines.

“We’re now looking at one of the biggest, most profitable underground gold mines in Ontario,” he told IM in a meeting in London this week. “That is a far cry from what the market saw when we first acquired the company. We have since more than tripled the reserve and resource base and continue to build confidence in adding further ounces.”

The Phase 3+ Expansion Study released earlier this year outlined a 2,400 t/d shaft-supported operation with average annual gold production of 287,000 oz, starting in 2026 upon completion of the sinking and equipping of a 1,373-m-deep shaft. This represents a 22% increase from the previous Phase 3 study and a 121% increase from the mid-point of 2022 production guidance of 130,000 oz.

McCluskey confirmed this week that pre-sinking activities at the expansion project had been completed by contractor Redpath, going down to 42 m depth (pictured). He expected full sinking activities to start up next year in line with the above guidance.

The addition of a shaft connected to low-carbon intensity grid power in Ontario will support higher mining rates with a smaller mobile fleet of haul trucks resulting in significantly lower diesel consumption at Island, according to the company. This is expected to drive a 35% reduction in greenhouse gas emissions over the mine life.

While the current plan at Island is to sink down to circa-1,400 m, the company made the decision to acquire a hoisting plant for the expansion that could operate down to depths of 2,000 m. This is an indication of the undefined potential at the mine, according to McCluskey, who admitted the shaft could be sunk to even deeper depths should drilling results justify this.

“It would not require too much more engineering or money to extend the shaft below the circa-1,400 m level, so that is something we will continue to weigh up as we conduct further drilling,” he said. “The Island story continues to grow and we continue to see a very profitable future at what will become one of the lowest cost underground mining operations in the province.”

Orefields Raise Boring, Cementation Canada to collaborate on mining project delivery in Scandinavia

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Sweden-based Orefields Raise Boring AB has established a Memorandum of Understanding (MoU) with Cementation Canada Inc that could see the two companies collaborate on projects in Scandinavia going forward.

Cementation, a global mine development contractor, complements Orefield’s’ mining services, which include pilot drilling, raiseboring, down-reaming, horizontal raiseboring and casting/grouting, it says, offering capability and experience to engineer and sink shafts, drive decline ramps, lateral development, production mining and mine construction to access and mine orebodies.

Additionally, the team’s offerings include full in-house engineering and design-supply services for crushing/screening and conveying systems that condition and deliver run-of-mine ore to the processing facility.

In addition to introducing expanded capabilities beneficial to the broader Scandinavian Region, the Orefields + Cementation Tier 1 Team bring innovative delivery model alternatives that reduce risk for the mine owner when compared with the conventional engineering procuement and construction (EPC) or design-bid-build approaches, they say.

For example, creative risk-reducing alternatives include:

  • Design-build-operate/maintain (DBOM)
    • DBOM + system ownership
    • Following an agreed period of operation, option to transfer ownership
    • Owner’s mine build & mining partner

Cementation explained: “Over the life of the facility, operations and maintenance expenses often far exceed the initial cost to design and build systems. Consequently, the design and construction of the system significantly impacts operational reliability and the resultant costs that accumulate over the years. Our DBOM approach, being performed by a single accountable venture, reduces risk inherent in spreading work packages between different organisations (as with EPC or design-bid-build approaches, for example). Simply put, the principle behind the DBOM delivery model is that we ‘pack our own parachute’, so we make sure it is done right from the beginning through to deployment.”

With this partnership specifically being established in Sweden for the benefit and added value to the Scandinavian Region, technical and professional labour resources, as well as the supply of materials, equipment and fabrication/construction, will be procured in the local regions where possible. Depending on the availability of qualified Scandinavian-based resources, secondary preference will be given to other European Region countries.

Redpath continues mechanised sinking evolution with S20+ deployment at Odyssey

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Redpath is continuing its focus on mechanised shaft sinking operations, with the latest example being the planned use of the hydraulic shaft mucker S20+ at the Canadian Malartic Partnership’s (CMP) Odyssey gold project in Quebec, Canada.

Redpath Canada was recently contracted by the CMP to sink a 6.5-m diameter, 1,800-m deep concrete lined shaft at Odyssey, a project that has the potential to become one of Canada’s largest and most technologically advanced underground gold mines.

CMP, which is 50:50 owned by Yamana Gold Inc and Agnico Eagle Ltd, previously laid out plans to extract 19,000 t of ore at an estimated grade of about 2.75 g/t gold and roughly 5,000 t/d of waste rock during peak operations at Odyssey. The ore will be processed at the operation’s existing plant, which will eventually be adapted to the future mine’s needs including shifting from 57,000 t/d to 20,000 t/d. The ore will be hauled to surface using Blair production hoists with use of both shaft bottom and mid-shaft ore handling systems.

The sinking concept at Odyssey includes the use of the S20+, which was built by Redpath Deilmann in Germany. A previous iteration of this machine, the S20, was used with success on four shaft projects in both soft rock – with an integrated tool package – and hard rock.

The S20+ offers similar capacity/productivity to a North American pneumatic telescopic boom mucker but with a much easier learning curve for operators, according to Kevin Melong, Vice President – Shafts and Technical Services, at Redpath Canada.

Unlike the RD S100, which can move independently of the galloway within the shaft via a telescopic boom, the S20+ is connected to the galloway, requiring the lowering of the galloway to move the mucker into position for mucking.

Melong added: “The S20+ does present some potential for concurrent mucking when in and around the shaft station construction/excavation, but, in general, does not act independent of the stage as in the S100 design.”

Fitted with a bucket as standard, the S20+ offers a maximum digging depth of 7.96 m and a bucket volume of 560 litres. It also offers good flexibility, with the bucket capable of six rotations per minute.

Alongside the S20+ and the aforementioned S100, Redpath has been mechanising the shaft sinking process in mining through the use of large-diameter raiseboring equipment and operation of Herrenknecht’s Shaft Boring Roadheader (in soft-to-medium rock). The company is also working with Herrenknecht on the development of the Shaft Boring Cutterhead, a machine developed for medium-to-hard rock applications up to 250 MPa UCS.

South32 making engineering and design headway at Hermosa project

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A stellar set of annual financial results has provided the ideal backdrop for South32 to update shareholders on its rapidly progressing Hermosa project in Arizona, USA.

Released late last month, the company’s 2022 financial year results showed off record earnings of $2.6 billion, record free cash flow from operations of $2.6 billion and record return on invested capital of 30.1%.

With group copper-equivalent production expected to increase by 14% in the next financial year, South32 looked to be well leveraged to in-demand metal markets at the right time.

The company has progressively been repositioning its portfolio toward metals critical for a low-carbon future, having already established a pipeline of high-quality development options. One of these high-quality development options is Hermosa.

Hermosa, which the company acquired outright back in 2018 as part of a takeover of Arizona Mining, is key to the company’s critical metals pursuit, having exposure to base and battery metals that are expected to grow in demand – both domestically in the US and internationally.

It is being designed as South32’s first ‘next generation mine’, according to Hermosa President, Pat Risner, with a series of technical reports highlighting its use of automation and technology to minimise its impact on the environment and target a carbon-neutral mining scenario in support of the group’s goal of achieving net zero operational greenhouse gas emissions by 2050.

These same reports also highlighted the potential to develop a sustainable, low-cost operation producing zinc, lead and silver from the Taylor deposit, with the bonus of possible battery-grade manganese output for rapidly growing domestic markets from the Clark deposit.

In the latest results, the company said it was devoting $290 million of growth capital expenditure in the 2023 financial year to progressing Hermosa as it invests in infrastructure to support critical path dewatering and progress study work for the Taylor Deposit. This is ahead of a planned final investment decision expected in mid-2023, which should coincide with the feasibility study.

South32 is devoting $290 million of growth capital expenditure in the 2023 financial year to progress Hermosa

Some $110 million of this was assigned to construction of a second water treatment plant (WTP2) to support orebody dewatering at the asset, alongside dewatering wells, piping systems and dewatering power infrastructure.

An additional $95 million was slated for engineering and initial construction ahead of shaft sinking at the operation, plus work to support power infrastructure and road construction.

The remaining amount was expected to support work across the broader Hermosa project, including Clark study costs and the Taylor feasibility study.

All signs from these results are that the company is laying the groundwork to develop this project ahead of that mid-2023 deadline.

In another sign of progress, South32 recently signed a “limited notice to proceed” for shaft engineering and design at Hermosa with contractor Redpath, Risner confirmed, adding that the award represented a positive step forward for the project.

“We look forward to continuing our engagement with local communities and all of our stakeholders as we make further progress with the project,” he said.

Redpath will no doubt be evaluating the technical studies that have been signed off to this point and informing future reports.

The PFS design for Taylor is a dual shaft mine which prioritises early access to higher grade mineralisation, supporting zinc-equivalent average grades of approximately 12% in the first five years of the mine plan. The proposed mining method, longhole open stoping, is similar to that used at Cannington, in Australia, and maximises productivity and enables a single stage ramp-up to the miner’s preferred development scenario of up to 4.3 Mt/y.

Yet, the Clark deposit opportunity – which has become even more tantalising with the US Government invoking the Defense Production Act and supporting the production of critical metals including manganese – could see the plan change.

The company says it may accelerate the prefeasibility study for the Clark deposit, which is spatially linked to the Taylor deposit. A scoping study has previously confirmed the potential for a separate, integrated underground mining operation producing battery-grade manganese, as well as zinc and silver from the deposit.

South32 previously said Clark has the potential to underpin a second development stage at Hermosa, with future studies to consider the opportunity to integrate its development with Taylor, potentially unlocking further operating and capital efficiencies.

With a PFS selection study expected later this year, investors and interested parties will soon know the role Clark could play in the wider Hermosa project.

What is easy to gauge already is that Hermosa is progressing on a track that many other development projects in in-demand sectors have gone down.

Woodsmith Shaft Boring Roadheaders about to re-start cutting process

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One of the most-watched shaft sinking projects in the sector right now is located in the UK, with the Woodsmith project in north Yorkshire having been on the radar for a number of reasons.

First off, it is a project that has changed hands recently.

Originally guided by Sirius Minerals, the 10 Mt/y project was acquired by Anglo American in 2020, a transaction that came with a fresh look at the whole project execution phase.

The change in ownership and re-assessment of plans drawn up by Sirius – a much smaller company guided by different investor pressures and operating procedures – led to Anglo American relieving DMC Mining, the lead shaft sinking contractor, of its duties.

Another reason for watching the project is the planned use of Shaft Boring Roadheader (SBR) technology from Herrenknecht.

After debuting at the Jansen potash project in Saskatchewan, Canada, where it excavated two 8-11 m diameter blind shafts down to circa-1,000-m-depth with the help of DMC as the contractor, SBR 2.0 – the second generation of the technology – was put to the test in Belarus at the Slavkaliy-owned Nezhinsky potash project. It ended up breaking shaft sinking records under the guidance of contractor Redpath Deilmann on a project to sink two 8-m diameter shafts (one to 750-m depth and one to 697-m depth).

Herrenknecht, with its experience in mechanised tunnelling, developed the SBR for the mechanised sinking of blind shafts in soft-to-medium rock. Based on the proven technology of the Herrenknecht Vertical Shaft Sinking Machine, the SBR offers improved safety performance compared with conventional shaft sinking methods while also achieving higher advance rates, according to the company.

The SBR is a 60-m tall, suspended shaft sinking machine, with 12 work decks and two service platforms. A telescopic, boom-mounted cutting head is used to precisely excavate rock via a partial-face cutting method. The cutting head works in a cycle, starting each cut from shaft centre to shaft wall, repeating until a layer of material is removed. Excavation proceeds in 1-m increments, followed by SBR lowering sequences.

The SBR was chosen for Woodsmith by Sirius over the conventional drill and blasting method due to its advantages in improving safety and schedule. This methodology, Sirius said, would allow the company to satisfy several operational objectives, moving away from the use of explosives and providing a safer, more predictable work method. Instead of a linear process, the SBR allows work to be completed concurrently as the shaft is sunk, as well as minimising damage to exposed host rock, and further improving safety while minimising downtime. Work decks above the cutting head allow workers to install shaft lining and tubbing as excavation continues, while a pneumatic mucking system removes waste rock.

The third generation of technology – which builds on the first two deployments with, among other things, the addition of two retractable robotic probes to test and grout the ground ahead for safer excavation and an additional control cabin on surface for more remote operation – is due to sink production and service shafts with 6.75-m diameters to depths of 1,594 m and 1,565 m, respectively, at Woodsmith based on the Sirius plan.

These SBRs are being supported by four triple sheaved winches from SMS SIEMAG and conveyors from Herrenknecht-owned H + E Logistik GmbH, among other support equipment.

Work on the service shaft commenced in 2021 with former Anglo American Chief Executive, Mark Cutifani, confirming in July of that year that the “first cut” with the SBR had taken place in the service shaft.

This progress was made while the company was still completing a detailed technical review on Woodsmith to ensure the technical and commercial integrity of the full scope of its design. This review has a particular focus on the sinking of the two main shafts, the development of the underground mining area, and the changes required to accommodate both increased production capacity and the more efficient and scalable mining method of using only continuous miners, Anglo American said.

Since the first cut was made in July 2021, however, Anglo American and Redpath Deilmann – which is now leading the sinking project as shaft sinking contractor – have been reviewing the existing plans for sinking with the SBRs, carrying out minor hardware changes on the machines and ensuring all staff have the appropriate training to facilitate the completion of the shaft sinking process. The Redpath Group is also involved in the drill-and-blast-based sinking for the materials transport system (MTS) shaft.

Various shaft sinking rates have been mooted in the past at Woodsmith, and Anglo American is currently working to develop the optimal solution for the facility based on technical standards.

The sinking at Woodsmith represents a different challenge to the two previous SBR projects conducted to this point.

For starters, there is no ground freezing expected to take place at Woodsmith – unlike what happened in Canada and Belarus. This process, while time consuming and only used to freeze unstable water-bearing strata around the shaft, can create more rock uniformity to aide consistent cutting rates.

There is also the MTS level to consider at Woodsmith, with plans to carry out lateral development work around the 360-m-level to join up the production shaft with this level where polyhalite ore will be transported along a 37-km tunnel to Wilton near the port. This means vertical cutting and loading may be halted while the MTS level connection is established.

All these factors, along with the performance of previous SBR work, will be incorporated into the engineering work Anglo American is carrying out at Woodsmith, but, in terms of the SBR, signs are that work on the service shaft could recommence shortly, with plans to start sinking in the production shaft by the end of the year.